We propose a new platform that leverages synthetic biology genetic circuits and micro/mesofluidic instrumentation to rapidly advance the field of organoids. Specifically, we will genetically engineer self- organizing tissues from human pluripotent stem cells into co-developed liver and pancreas organoids possessing vascularization and other mature properties, such as adult level albumin production. The application of synthetic biology to organoid development (programmable organoids) provides an exciting new opportunity for engineering and testing of organoids encoding live cell sensors of cell state and for embedding circuits that express cell-type and cell-state specific transcription factors. We will engineer novel microfluidic and mesofluidic platforms to enable low cost and high throughput development and testing of programmable organoids. Our hypothesis is that co-development of hiPSC-derived liver and pancreas provides cell-cell interactions that contribute to vascularization and other important elements in organoid development that will lead to mature organ formation. To test our hypothesis, we will genetically encode live-cell sensors to monitor liver organoid develop, co-develop liver and pancreas organoids, and create genetic circuits that lead to mature organoid formation. We will use synthetic classifier genetic circuits that evaluate changes in cell state in real time, and generate relevant protein outputs for driving differentiation in a cell-type specific manner. This these circuits will enable autonomous generation of new and improved versions of organoids, including mature liver organoids and co-developed liver/pancreas organoids. Determining the precise spatiotemporal nature of cell state transitions and the relevant transcription factors to drive differentiation is not only essential for creating new and effective organoid developmental programs, but will also provide important scientific insights to understanding the fine aspects of differentiation and co-development. Successful achievement of our aims will have a broad impact in the areas of gene therapy, drug testing, and personalized medicine. For example, the ability to co-develop matched organoid systems will enable patient-specific drug development (e.g. for cancer therapy) that is more accurate than expensive and controversial alternatives, such as the use of humanized mice. This work will also support the long-term goal of producing mature organoids and organ systems suitable for transplantation.